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Manzanita leafgall aphidOn this page: Identification & Distribution Other aphids on the same host Damage & Control
Identification & Distribution
Feeding by the aphid Tamalia coweni on manzanita (Arctostaphylos) leaves induces red or reddish-green elongate to pod-shaped galls (see first two pictures below) within which the aphids feed and develop.
First picture above copyright John Rusk, second picture above copyright Eddie Dunbar,
Adult apterae of Tamalia coweni (see first picture below) are dull dirty yellow to dark green or blackish, with variably-developed dark sclerotic cross-bands on the tergites and sternites (cf. Tamalia inquilinus adult apterae, which have the tergum entirely sclerotic and coloured dusky dark). The head, appendages and genital plate are dark. The antennae are usually 4-segmented (cf. Tamalia inquilinus, which has 5 antennal segments). The apical rostral segment (RIV+V) is 0.9-1.5 times the length of the second hind tarsal segment (HT II) and bears 4-13 accessory hairs (cf. Tamalia dicksoni and Tamalia milleri, which have RIV+V 1.8-2.1 times as long as HT II, with 18-39 accessory hairs). The dorsal body surface is ornamented with numerous small spicules. Siphunculi are present as pores on small flattened cones. The body length of adult apterae is 1.25-1.5 mm. Immature Tamalia coweni are greenish without any cross bands (see second picture below, which shows numerous exuvia in the gall along with a fourth instar alatiform nymph and younger immatures).
First picture above copyright James Bailey, second picture above copyright Damon Tighe,
The two pictures below are clarified mounts of an apterous and alate Tamalia coweni.
Tamalia coweni feeds on manzanitas and bearberries (Arctostaphylos spp.) inducing characteristic galls. Tamalia species have a unique biology amongst aphids including an alate ovipara and no host alternation: all other galling-aphid taxa are host-alternating or secondarily monophagous (Miller, 2005 ). The overwintering eggs hatch in late winter or spring and the emerging fundatrices move to the leaves where they feed. Both the fundatrix and third generation aphids (referred to as foundresses) of Tamalia coweni induce galls. Both fundatrices and foundresses are wingless and generally remain within the gall, alternating with winged individuals, which disperse from the galls. In the final, sexual generation in fall, both males and oviparae are winged and disperse before mating. The eggs are laid on bark at the base of the host plant. The manzanita leafgall aphid is found in western North America, across boreal Canada to Ontario, and south through western USA to Mexico.
Other aphids on the same host
Tamalia coweni has been recorded on at least 13 species of manzanita (Arctostaphylos canescens, Arctostaphylos glandulosa, Arctostaphylos glauca, Arctostaphylos insularis, Arctostaphylos manzanita, Arctostaphylos nevadensis, Arctostaphylos patula, Arctostaphylos pumila, Arctostaphylos pungens, Arctostaphylos tomentosa, Arctostaphylos uva-ursi, Arctostaphylos viridissima, Arctostaphylos viscida).
Damage and control
Severe infestations may slow the growth of the plant. Production of honeydew may result in the growth of dark sooty mould on the leaves. However, use of chemical control methods is seldom justified, and natural enemies will most likely reduce the number of aphids and their galls.